New Breed of Optical Soliton Wave Discovered

Optical microcavities in which the solitons were created. Credit: Qi-Fan Yang/Caltech

The retraction of the nonlinear and dispersive effect of the medium causes soliton. Although, soliton wave maintains its shape while it propagates at a constant velocity. They are limited waves mimics as particles that travel across space. Additionally, with water waves, solitons can occur as light waves. Kerry Vahala, applied scientist from California Institute of Technology with his team, discovered a new type of optical soliton wave.

This new optical soliton wave moves in the wake of other soliton waves by joining a ride on and feeding off of the energy of the other wave. Vahala and team first analyse light solitons. They rotate it into optical microcavities.

This new optical soliton wave has various applications including in the creation of highly accurate optical clocks and in microwave oscillators.

But according to previous studies, a soliton has never been observed behaving in a dependent almost parasitic way.

Vahala said, “This new soliton rides along with another soliton—essentially, in the other soliton’s wake. It also syphons energy off of the other soliton so that it is self-sustaining. It can eventually grow larger than its host.”

Scientists compared this new soliton with pilot fish. The pilot fish is carnivorous tropical fish that swim next to a shark so they can pick up scraps from the shark’s meals. The pilot fish decreases water drag on their body so that they can travel with less effort. Scientists named this soliton as Stokes soliton. The soliton’s ability to relatively match the position and shape of the original soliton.

Scientists use laser input to provide energy to solitons. This energy is not directly absorbed by the Stokes soliton, the pilot fish. Instead, the energy is consumed by the “shark” soliton. But then, scientists found that the energy is pulled away by the pilot fish soliton, which grows while the other soliton shrinks.

Qi-Fan Yang, Caltech’s graduate student, said, “We confirmed that the signal was not an artifact of the instrumentation by observing the signal on two spectrometers. We then knew it was real and had to figure out why a new soliton would spontaneously appear like this.”

Xu Yi, the graduate student, said, “Once we understood the environment required to sustain the new soliton, it became possible to design the microcavities to guarantee their formation and even their properties like wavelength—effectively, color.”